<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		 <style>
		        div {
		            width: 100px;
		            height: 100px;
		            background: red;
		            text-align: center;
		            line-height: 90px;
		            color: white;
		        }
		        div:hover {
		            width: 300px;
		            height: 300px;
		        }
		    </style>
		</head>
		<body>
		<div>放上来</div>
	</body>
</html>